Color printer and printing method using the same

ABSTRACT

A color printer provided with ink jet heads comprising three trains of nozzle holes for respectively discharging different colored ink, each train of nozzle holes composed of a plurality of nozzle holes which are arranged at intervals of three pitches in the auxiliary scanning direction, and disposed at equal intervals in the main scanning direction while shifting every one pitch in the auxiliary scanning direction wherein different colored inks are discharged and sequentially superimposed over one another on a recording sheet to synthesize colors. The color printer further comprises control means for controlling the ink jet heads by discharging only one colored ink through the nozzle holes of any one of the three trains to make a print on the recording sheet as the first main scanning, then discharging ink through the nozzle holes of said train and another train adjacent to said train of nozzle holes to make a print as the scanned main scanning while they are shifted by one pitch in the auxiliary scanning direction, and thereafter discharging ink through the nozzle holes of the three trains to make a print as the next main scanning while they are shifted by one pitch in the auxiliary scanning direction, so as to make a print which is regular in sequence of superimposition of colors.

TECHNICAL FIELD

The present invention relates to a printer, particularly to a colorprinter for printing multiple colors provided with ink jet heads and aprinting method using the color printer.

BACKGROUND TECHNOLOGY

A method of printing multiple colors by synthesizing colors on arecording medium (paper) is known, for example, as described in JapanesePatent Laid-Open Publication No. 3-244550.

According to this publication, there are provided a plurality of nozzleholes comprising first, second and third groups of nozzle holesrespectively provided on the nozzle surfaces of ink jet heads fordischarging magenta, cyan and yellow (hereinafter abbreviated as M, Cand Y) ink, group by group. The multiple colors are printed by mountingthe ink jet heads on a carriage and scanning in main and auxiliaryscanning direction along the recording medium, and discharging ink fromthe nozzle holes.

In such a method, it is possible to synthesize printed dots ofsynthesized red, green and blue (hereinafter abbreviated as R, G and B)by precisely superimposing the printed dots of different primary colors(any of M, C and Y) over one another while shifting location by onepitch, or by integral times of one pitch, in the main or auxiliaryscanning direction.

That is, it is possible to print synthesized multiple colors having nosmudge therein with a relatively simple mechanism while performing ascanning operation which is not so different from that when printingmonochrome. Accordingly, the multiple color printer using this methodhas quickly become widespread.

There are the following three kinds of methods employed in theaforementioned printing method.

First Method

This is a method, as shown in FIGS. 17 and 18, for making a print usingprinting heads on which groups of nozzle holes of different colors of M,C and Y are sequentially arranged in the auxiliary scanning direction.

This method comprises synthesizing colors by performing the mainscanning while shifting every n pitch corresponding to respective groupsof nozzle holes in the auxiliary scanning direction so that printed dotsof different primary colors are superimposed over one another. Hereupon,the sequence of superimposition of the primary colors is always constantregardless of the normal or reverse direction of the main scanningdirection (which is the same as the order of arrangement of the groupsof different colors in the auxiliary scanning direction).

Accordingly, the tone of the same color in the printed image is alwaysuniform even if the printing speed increases with bidirectional printingscanning. However, this is contrary to the demand for miniaturizationand compactness of the apparatus because the dimensions of the heads inthe auxiliary scanning direction increase, and hence the volume neededfor the entire apparatus increases.

Second Method

This is a method, as shown in FIG. 19, for making a print using printingheads on which groups of n nozzle holes are provided for each differentcolor of M, C and Y, and are sequentially arranged in the main scanningdirection.

According to this method, the dimensions of the heads in the auxiliaryscanning direction decrease, and hence the volume needed for the entireapparatus decreases. However, when printing, printed dots of differentprimary colors are superimposed over one another by n lines (width of ndots) under one-time main scanning which is not accompanied by scanningin the auxiliary scanning direction. Further, printed dots of differentprimary colors are superimposed over one another by n subsequent lines(by the lines extending from the n+1 line to the 2n line from thebeginning) by performing scanning in the main scanning direction whileshifting every next n pitch.

At this time, the sequence of superimposition of primary colors isreversed by reversing the main scanning direction, thereby changing thetone of the synthesized colors. Accordingly, when bidirectional printingscanning is performed, streaks are produced on the printed image every npitch distance in the auxiliary scanning direction owing to the changeof tone, thereby deteriorating the quality of the image.

Third Method

This is a method, as shown in FIG. 20, for making a print using printingheads on which groups of nozzle holes of different colors of M, C and Yare sequentially arranged in the main scanning direction while they areshifted by every one pitch (P) of printed dots in the auxiliary scanningdirection.

In this case, the interval between respective groups of nozzle holes isthree times as large as the pitch of the printed dots. Accordingly, theheads are easily manufactured. However, it is impossible to superimposeprinted dots over one another by one time main scanning. Accordingly, itis necessary to superimpose printed dots of colors over one another byperforming the main scanning while shifting the printed dots every onepitch (1/3 of the interval between nozzle holes of each group) in theauxiliary scanning direction.

Accordingly, in the first main scanning performed in first step ST1 asshown in FIG. 20, ink is prohibited from being discharged through afirst nozzle hole M1 of an M group and a first nozzle hole C1 of a Cgroup, while it can be discharged through other nozzle holes.

In FIG. 20, hatched portions represent colors to be printed inrespective steps. Each dot represents that the printing is sequentiallyperformed from the color positioned to its left.

Subsequently,in the second main scanning performed in second step ST2after shifting by one pitch in the auxiliary scanning direction (sheetfeeding by one pitch in a sheet feeding direction as denoted by the openarrow in the same figure), ink is prohibited from being dischargedthrough the first nozzle hole M1 of the M group and ink can bedischarged through other nozzle holes, if need be.

Next, in the third main scanning performed in third step ST3 aftershifting further by one pitch in the auxiliary scanning direction (sheetfeeding by one pitch), ink can be discharged through all nozzle holes.

Even in the fourth main scanning performed in fourth step ST4 afterfurther shifting by (n-1)×3+1 pitches in the auxiliary scanningdirection, ink can be discharged through all nozzle holes. Further, evenin the fifth main scanning performed in fifth step ST5 after shifting byone pitch in the auxiliary scanning direction, ink can be dischargedthrough all nozzle holes.

Even in the sixth main scanning performed in sixth step ST6 aftershifting by one pitch in the auxiliary scanning direction, ink can bedischarged through all nozzle holes. The sequence of colors of printeddots in each line where the printed dots are superimposed over oneanother by the main scanning in sixth step ST6 follows the order: YCM,MYC, CMY, YCM, MYC, . . . YCM, YC, Y from the leading line, which is thesame state as shown in third step ST3.

Accordingly, in the main scanning, performed in seventh step ST7 aftershifting by one pitch in the auxiliary scanning direction uponcompletion of printing, ink can be discharged only through the last(nth) nozzle hole Mn of the M group and the last nozzle hole Cn of the Cgroup.

In eighth step ST8, after shifting by one pitch in the auxiliaryscanning direction, ink can be discharged only through the last nozzleMn of the M group to complete the printing.

That is, the print is made from the start of printing through the stepsof ST1, ST2, ST3, ST4, ST5, ST6, ST4, ST5, ST6, . . . ST4, ST5, ST6, ST7and ST8. At this time, the sequence of superimposition of the printeddots of colors as a whole is as follows from the leading line, namely:YCM, MYC, CMY, YCM, MYC, . . . CMY, YCM, YCM, YCM, YCM, MYC, CMY, YCM,MYC, . . . CMY, YCM, YCM, YCM, MYC, CMY, YCM, MYC, . . . CMY, YCM, YCMand YCM.

Regarding the sequence of Y and C according to the sequence of colors asset forth above, it is changed in some lines such as YC, YC, CY, YC, . .. . Even in the order of C and Y and M and Y, the reverse sequence ofcolors occurs likewise in some lines.

If the reverse of the sequence of colors occurs, R, G and B which aresynthesized colors of each line are changed in tone, thereby producingstreaks that deteriorate the quality of the image.

The sequence of superimposition of the printed dots of colors is alwaysfixed regardless of the forward or reverse direction of the mainscanning direction. Accordingly, such streaks can not be removed even ifthe main scanning direction is selected in either direction (i.e., evenin the normal printing method or in the bidirectional printing scanningmethod).

It is, therefore, an object of the invention to remove streaks inprinted images which are produced by the change of sequence of thesuperimposition of colors using a color printer provided with the inkjet heads which are used in the aforementioned third method.

It is another object of the invention to provide a small-sized colorprinter capable of solving the above problem and using ink jet headswhich are easily manufactured, and a printing method capable of printingmultiple colors which are uniform in image quality even if one-wayprinting or bidirectional printing is performed.

DISCLOSURE OF THE INVENTION

The color printer of the invention is provided with ink jet headscomprising three trains of nozzle holes for respectively dischargingdifferent colored ink, each train of nozzle holes composed of aplurality of nozzle holes which are arranged in the auxiliary scanningdirection and spaced by three pitches, and the nozzle holes of the threetrains of nozzle holes are disposed at equal intervals in the mainscanning direction while shifting every one pitch in the auxiliaryscanning direction wherein different colored inks are sequentiallysuperimposed over one another on a recording medium (paper) tosynthesize colors so as to male a color print, and to achieve the aboveobject, the color printer further comprises control means forcontrolling the ink jet heads to make a print which is regular in thesequence of superimposition of colors by taking each of the followingsteps:

discharging only one colored ink through the nozzle hole of a firsttrain of nozzle hole which is any one of the three trains of nozzleholes to make a print on the recording medium as the ink jet heads arescanned in the first train of main scanning direction in a first step;

discharging ink through the nozzle holes of the first train of nozzleholes and the nozzle holes of a second train of nozzle holes adjacent tothe first train of nozzle holes to make a print on the recording mediumas the ink jet heads are scanned in the main scanning direction whilethey are shifted by one pitch in the auxiliary scanning directionrelative to the recording medium in a second step;

discharging ink through all nozzle holes of the first, second andremaining third trains of nozzle holes to make a print on the recordingmedium as the ink jet heads are scanned in the main scanning directionwhile they are shifted by one pitch in the auxiliary scanning directionrelative to the recording medium in a third step;

discharging ink through all nozzle holes of the second and third trainsof nozzle holes and only through the last nozzle hole of the first trainof nozzle holes in the auxiliary scanning direction to make a print onthe recording medium as the ink jet heads are scanned in the mainscanning direction while they are shifted by one pitch in the auxiliaryscanning direction relative to the recording medium in a fourth step;

discharging ink through all nozzle holes of the third train of nozzleholes and only through the last nozzle holes of the first and secondtrains of nozzle holes in the auxiliary scanning direction to make aprint on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in a fifthstep;

discharging ink through all nozzle holes of the first train of nozzleholes and only through the first nozzle holes of the second and thirdtrains of nozzle holes in the auxiliary scanning direction to make aprint on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by (n-1)×3+1 pitches (nis the number of nozzle holes of each nozzle train) in the auxiliaryscanning direction relative to the recording medium in a sixth step;

discharging ink through all nozzle holes of the first and second trainsof nozzle holes and only through the first nozzle hole of the thirdtrain of nozzle holes in the auxiliary scanning direction to make aprint on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in aseventh step;

executing printing operations sequentially in the third to seventhsteps;

discharging ink only through the last nozzle holes of the second andthird trains of nozzle holes in the auxiliary scanning direction to makea print on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in a stepfollowing the fifth step when ending the printing (in a eighth step);and

then discharging ink only through the last nozzle hole of the thirdtrain of nozzle holes in the auxiliary scanning direction to make aprint on the recording medium while the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium so as toend the printing.

With the provision of this control means, the sequence ofsuperimposition of colors of ink is always in the order as follows.

1. First color of ink which is discharged through the nozzle holes ofthe first train of nozzle holes.

2. Second color of ink which is discharged through the nozzle holes ofthe second train of nozzle holes adjacent to the first train of nozzleholes.

3. Third color of ink which is discharged through the nozzle holes ofthe third train of nozzle holes adjacent to the second train of nozzleholes.

Since the sequence of superimposition of colors is regular as mentionedabove, there does not occur a case where image tone is changed toproduce streaks in the printed image. Accordingly, multiple colorsprinting which are uniform in image quality can be printed.

Further, there are advantages that the reduction of printing speed issmall, and streaks produced between the printed continuous portions arenot prominent even if there occurs an error in sheet feeding amount whenthe ink jet heads are largely shifted in the auxiliary scanningdirection relative to the recording medium in response to the number ofnozzle holes of respective trains of nozzle holes as set forth in theabove step 6.

Further, supposing that the control means set forth above is firstcontrol means, it is possible to provide selection means for selectingeither the first control means or the following second control means tocontrol the ink jet heads set forth above when printing.

The second control means comprises means for controlling the ink jetheads to make a print which is irregular in the sequence ofsuperimposition of colors, by discharging ink through all nozzle holesto make a print on the recording medium while prohibiting ink from beingdischarged through respective first nozzle holes of two of the trains ofnozzle holes of the three trains of nozzle holes (first nozzle holes inthe auxiliary scanning direction) as the ink jet heads are scanned inthe main scanning direction, then discharging ink through all nozzleholes to make a print on the recording medium while prohibiting ink frombeing discharged only through the first nozzle hole of either of theaforementioned two trains of nozzle holes (first nozzle hole in theauxiliary scanning direction) as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium, andthereafter discharging ink through all nozzle holes of the three trainsof nozzle holes to make a print on the recording medium as the ink jetheads are scanned in the main scanning direction while they are shiftedby one pitch in the auxiliary scanning direction relative to therecording medium.

With such an arrangement, it is possible to select the print modedepending on the object of printing and type of print data, namely, toselect print mode using the first control means which is excellent inprint image quality or to select the printing using the second controlmeans which is fast in print speed.

The printing method using a color printer according to the invention ischaracterized in making a print on a recording medium which is regularin sequence of superimposition of colors by making each print in thesame steps as respective steps executed by the first control means setforth above.

Further, suppose that the printing method of making a print which isregular in sequence of superimposition of colors is a first printingmethod, it may be possible to make a print by arbitrarily orautomatically selecting the first printing method or a second printingmethod which is irregular in sequence of superimposition of colors bymaking each print in the same steps as respective steps executed by thesecond control means set forth above.

The selection of the aforementioned printing methods can be performed,for example, by the operation of an external member or by control datafrom a host for transmitting print data.

The selection may be performed automatically in response to printingmodes for print data in the manner of selecting the second printingmethod if the printing mode is a photographic mode and of selecting thefirst printing method if the printing mode is a graphic mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the main portion of a mechanism ofa color printer of the invention.

FIG. 2 is a view showing an example of arrangement of nozzle holesdefined in heads of the color printer shown in FIG. 1.

FIG. 3 is a block diagram showing an example of the construction of acontrol system mainly explaining a controller 12 of the color printer 20shown in FIG. 1.

FIG. 4 is a flow chart showing procedures in a printing method accordingto a first embodiment of the invention using the color printer shown inFIG. 1.

FIG. 5 is a view for explaining a state of printing according to theprinting method in FIG. 4.

FIG. 6 is a flow chart showing procedures in the printing methodaccording to a second embodiment of the invention using the colorprinter shown in FIG. 1.

FIG. 7 is a view for explaining a state of printing according to theprinting method in FIG. 6.

FIG. 8 is a block diagram showing the construction of a control systemin a color printer which is used in the printing method according to athird embodiment of the invention.

FIG. 9 is a flow chart showing procedures in the printing method of thesecond embodiment which is executed by the color printer having thecontrol system shown in FIG. 8.

FIG. 10 is a flow chart showing an example of a printing procedure inthe case of selecting a printing method based on control data suppliedfrom a host 13 in the color printer having the control system shown inFIG. 8.

FIG. 11 is a view showing another example of a printing procedure in thecase of selecting a printing method by input through an operation key 16in FIG. 8.

FIG. 12 is a view showing printed dots of a photograph mode in aprinting method according to a fourth embodiment of the invention.

FIG. 13 is a view showing an example of printed dots of a graphic modein the same embodiment.

FIG. 14 is a flow chart showing procedures at a host side and at aprinter side according to the printing method of the fourth embodiment.

FIG. 15 is a block diagram showing an example of the construction of acontrol system in a color printer which is used in a printing methodaccording to a fifth embodiment of the invention.

FIG. 16 is a flow chart showing the printing procedure in a test patternprinting mode using the color printer having the control system shown inFIG. 15.

FIG. 17 is a view showing an example of the arrangement of nozzle holesdefined in heads of a conventional color printer.

FIG. 18 is a view showing another example of the arrangement of nozzleholes defined in heads of the conventional color printer.

FIG. 19 is a view showing still another example of the arrangement ofnozzle holes defined in heads of the conventional color printer.

FIG. 20 is a view explaining a third example of printing method usingthe conventional color printer.

BEST MODE FOR CARRYING OUT THE INVENTION

Working examples of the invention will now be described in more detailwith reference to the attached drawings.

Working Example of Color Printer

A color printer according to the working example of the invention willnow be described with reference to FIG. 1 to FIG. 3.

FIG. 1 is a view showing a main portion of a mechanism of a colorprinter of the invention, and FIG. 2 is a view showing the arrangementof nozzle holes of the color printer 20 for discharging the primarycolors M, C and Y.

A carriage 1 in FIG. 1 mounts thereon an ink tank 2M for M, an ink tank2C for C, an ink tank 2Y for Y, an ink tank 2BK for black (BK), and anink jet head 3M for M, an ink jet head 3C for C, an ink jet head 3Y forY, an ink jet head 3BK for BK. These ink tanks and ink jet heads arearranged in the order of M, C, Y and BK from the left relative to thedirection of a guide rail 6 for guiding the carriage 1.

A carriage motor 7 moves the carriage 1 reciprocally along the guiderail 6 via a timing belt 8 which extends between pulleys 4 and 5.

A platen 9 which is disposed parallel to the guide rail 6 guides arecording sheet (media) 10 so as to approach and oppose the ink jetheads 3M, 3C, 3Y and 3BK. A sheet feed motor 11 rotates the platen 9 tofeed the recording sheet 10 in a direction of the arrow A.

Nozzle holes are arranged, relative to the recording sheet 10, on thesurfaces of the ink jet head 3M for M, the ink jet head 3C for C, andthe ink jet head 3Y for Y, respectively opposing the recording sheet 10as shown in FIG. 2.

That is, an M group is disposed at the left end and it is composed of nnozzle holes M1, M2, . . . Mn of the ink jet head 3M for M which eachdischarge M ink and are arranged in the auxiliary scanning direction(direction opposite to sheet feeding direction: downward in FIG. 2) andspaced at three pitches (3P) of recorded dots, as described later.

A C group is disposed at the right side of the M group and spaced at agiven interval in the main scanning direction (moving direction of thecarriage) while it is shifted further by one pitch in the auxiliaryscanning direction (P: 1/3 of the interval between nozzle holes) and itis composed of n nozzle holes C1, C2, . . . Cn of the ink jet head 3Cfor C which each discharge C ink and are arranged in the auxiliaryscanning direction and spaced at three pitches.

A Y group is disposed at the right side of the C group and at a giveninterval in the main scanning direction while it is shifted further byone pitch in the auxiliary scanning direction (1/3 of the intervalbetween the nozzle holes), and it is composed of n nozzle holes Y1, Y2,. . . Yn which are respectively defined in the ink jet head 3Y for Y fordischarging Y ink and are arranged in the auxiliary scanning directionand spaced at three pitches. In the color printer 20 shown in FIG. 1,the ink jet heads 3M, 3C, 3Y and 3BK, the carriage motor 7, the sheetfeed motor 11, etc., are each controlled by a controller 12 serving ascontrol means. The controller 12 is structured to be controlled by ahost 13 such as a personal computer, etc.

An indicator 15 and an operation key 16 are respectively provided on anoperation panel 14 serving as an I/O interface of the color printer 20to an external device.

In the color printer 20, the ink jet head 3BK for BK is used formonochrome printing in black. The object in achieving the printingmethod according to the invention, described later, is printingmonochrome or multiple colors using the ink jet heads 3M for M, 3C for Cand 3Y for Y.

FIG. 3 is a block diagram showing an example of construction of acontrol system explaining mainly the controller 12 shown in FIG. 1.

The controller 12 comprises a CPU 17, a program memory (ROM) 18, aworking memory (RAM) 19, a data memory (RAM) 21, an interface 22 for thehost 13, an input port 23 for a sensor 30 including various sensors inthe color printer, an input port 24 for the operation key 16, a gatearray 25, a head control circuit 27, an output port 28 for a driver 35of the carriage motor 7 and the sheet feed motor 11, and an output port29 for the indicator 15.

A power supply circuit 31 supplies necessary voltage or power to thehead control circuit 27, ink jet heads 3 (respective ink jet heads 3Mfor M, 3C for C, 3Y for Y and 3BK for BK in FIG. 1 are generallyreferred to as the ink jet heads 3), and to the controller 12, thedriver 35, and the indicator 15, although the connecting lines betweenthe power supply circuit 31 and these components are omitted for ease ofillustration.

The gate array 25 is a logical circuit for converting print data to beinputted from the host 13 into M, C and Y data corresponding to a firstprinting method of the invention, described later, and storing theconverted data into the data memory.

The controller 12 which serves as control means entirely controlsrespective components including the ink jet heads 3 by microcomputersmainly composed of the CPU 17, thereby executing the printing methods ofthe invention, described later.

Printing Method according to First Embodiment

The printing method to be executed by the color printer 20 according tothe first embodiment of the invention will now be described.

FIG. 4 is a flow chart showing steps in the printing operation, and FIG.5 is a view for explaining the sequence of colors to be printedcorresponding to the respective steps.

Preparation for printing is done by starting up the color printer 20 andsetting the carriage 1 at the printing start position.

First of all, in first step ST1 shown in FIG. 4 and FIG. 5, ink isprohibited from being discharged through all nozzle holes of the M groupand C group. A main scanning is performed by moving the carriage 1 in astate where ink can be discharged from all nozzle holes of the Y groupalone so that dots are printed every two lines based on the print dataas shown in FIG. 5.

FIG. 5 shows a case where the number n of the nozzle holes of each groupis expressed as n=3, and the nozzle holes capable of discharging inkhave entirely discharged ink (this is applied hereinafter).

Next in second step ST2, the carriage is shifted relatively by one pitchof printed dots (P: 1/3 of the interval between nozzle holes) in theauxiliary scanning direction by feeding the recording sheet 10 in thedirection as denoted by the arrow A shown in FIG. 1 (hereinafter toreferred to as "one pitch sheet feed" in FIG. 4), that is, after onepitch auxiliary scanning, the main scanning is performed in a statewhere ink is prohibited from being discharged through all nozzle holesof the M group while ink can be discharged through all nozzle holes ofthe C group and Y group to print dots based on the print data.

As a result, as shown in FIG. 5, there is produced a line where no dotis printed, a line where dots of Y alone are printed and a line wheredots of Y and C are printed while they are superimposed over one anotherin this order.

In third step ST3, the horizontal scanning is performed in a state whereink can be discharged through all nozzle holes of the M group, C groupand Y group to make a dot print based on the print data after thecarriage 1 is subjected to auxiliary scanning by one pitch uponcompletion of one pitch sheet feed. Accordingly, there is produced aline where dots of Y alone are printed, a line where dots of Y and C areprinted while they are superimposed over one another in this order and aline where dots of Y, C and M are printed while they are superimposedover one another in this order.

In fourth step ST4, the main scanning is performed in a state where inkcan be discharged through all nozzle holes of the M group and C groupand through an nth nozzle hole Yn of the Y group (Y3 in the case of FIG.5) to make a dot print based on the print data while ink is prohibitedfrom being discharged through nozzle holes of the Y group other than thenozzle hole Yn after the carriage 1 is subjected to the auxiliaryscanning by one pitch upon completion of one pitch sheet feed.

Accordingly, although there is produced a line where dots of Y alone areprinted, a line where dots of Y and C are printed while they aresuperimposed over one another in this order and a line where dots of Y,C and M are printed while they are superimposed over one another in thisorder, the number of lines of Y alone are reduced, and the number oflines of Y and C and the number of lines of Y, C and M are increased,compared with the case of third step ST3.

In fifth step ST5, the main scanning is performed in a state where inkcan be discharged through all nozzle holes of the M group and through annth nozzle hole Cn of the C group (C3 in FIG. 5) and through an nthnozzle hole Yn of the Y group (Y3 in FIG. 5) to make a dot print basedon the print data while ink is prohibited from being discharged throughnozzle holes other than the nozzle holes Cn and Yn of the C and Y groupsafter the carriage 1 is subjected to auxiliary scanning by one pitchupon completion of one pitch sheet feed.

Accordingly, dots of Y, C and M are printed while they are superimposedover one another in this order except in the last two lines as shown inFIG. 5. The dots of Y alone are printed in the last line, and dots of Yand C are printed while they are superimposed over one another in thisorder in the second line from the last line.

Subsequently as shown in FIG. 4, it is judged whether the procedure ofprogram continues or not, and the program goes to an eighth step ST8 ifit does not continue while the program goes to a sixth step ST6 if itcontinues.

In sixth step ST6, the main scanning is performed in a state where inkcan be discharged through a first nozzle hole M1 of the M group, a firstnozzle hole C1 of the C group and all nozzle holes Y1 . . . Yn of the Ygroup to make a dot print based on the print data while ink isprohibited from being discharged thorough other nozzle holes after therecording sheet 10 is fed by (n-1)×3+1 pitches (seven pitches in FIG.5), and the carriage 1 is shifted by the same pitch relatively in theauxiliary scanning direction, namely, it is subjected to auxiliaryscanning by seven pitches.

As a result, dots of Y, C and M are printed while they are superimposedover one another in this order in the n×3 line from the last line (ninthline from the last line in FIG. 5) and the lines in ascending order,i.e. upward lines thereof. The dots Y and C are printed while they aresuperimposed over one another in this order in the n×3-1 line from thelast line (eighth line from the last line in FIG. 5). In the n×3-2 linefrom the last line (seventh line from the last line in FIG. 5) and thelines in descending order, i.e. downward lines thereof, the dots areprinted in the same manner as in first step ST1.

In seventh step ST7, the main scanning is performed in a state where inkcan be discharged through the first nozzle hole M1 of the M group andall nozzle holes of the C group and Y group to make a dot print based onthe print data while ink is prohibited from being discharged throughother nozzle holes after the carriage 1 is subjected to auxiliaryscanning by one pitch upon completion of one pitch sheet feed.

As a result, the dots of Y, C and M are printed while they aresuperimposed over one another in this order in the n×3 line from thelast line (ninth line from the last line in FIG. 5) and the upward linesthereof. In then n×3-1 line from the last line (eighth line from thelast line in FIG. 5) and downward, the dots are printed in the samemanner as in second step ST2.

In the next step (eighth step from the first), the operation as made inthird step ST3 is performed again. That is, the main scanning isperformed in a state where ink can be discharged through all nozzleholes of the M group, C group and Y group to make a dot print based onthe print data after the carriage 1 is subjected to auxiliary scanningby one pitch upon completion of one pitch sheet feed.

As a result, the dots of Y, C and M are printed while they aresuperimposed over one another in this order in the n×3 line from thelast line (ninth line from the last line in FIG. 5) and the upward linesthereof. In the n×3 line from the last line (ninth line from the lastline in FIG. 5) and the downward lines thereof, the dots are printed inthe same manner as at first in third step ST3.

Further, in the next step (ninth step from the first), the operation infourth step ST4 is performed.

As a result, the dots of Y, C and M are printed while they aresuperimposed over one another in this order in the n×3 line from thelast line (ninth line from the last line in FIG. 5) and the upward linesthereof. In the n×3 line from the last line and the downward linesthereof, the print state becomes the same as at first in the fourth stepST4.

In such a manner, the program returns to third step ST3 after executingthe operations respectively in fifth step ST5, sixth step ST6 andseventh step ST7, and thereafter the operations in third to seventhsteps ST3 to ST7 are repeated.

Meanwhile, when the printing is completed, the programs in eighth stepST8 and a ninth step ST9 are sequentially executed following the fifthstep ST5.

In eighth step ST8, the main scanning is performed in a state where inkcan be discharged through an nth nozzle hole Mn of the M group (M3 inFIG. 5) and an nth nozzle hole Cn of the C group (C3 in FIG. 5) to makea dot print based on the print data while ink is prohibited from beingdischarged through other nozzle holes after the carriage 1 is subjectedto auxiliary scanning by one pitch upon completion of one pitch sheetfeed.

Accordingly, the dots are printed while they are superimposed over oneanother in the order of Y and C only in the last line. The dots areprinted while they are superimposed over one another in the order of Y,C and M in all the remaining lines.

Next in ninth step ST9, the main scanning is performed in a state whereink can be discharged through the nth nozzle hole Mn of the M group (M3in FIG. 5) to make a dot print based on the print data while ink isprohibited from being discharged through other nozzle holes after thecarriage 1 is relatively subjected to the auxiliary scanning by onepitch upon completion of one pitch sheet feed. The dots are printedwhile they are superimposed over one another in the order of Y, C and Min all the lines. In such a manner, the printing operation using the inkjet heads of Y, C and M is completed.

According to the above mentioned printing method, since dots of primarycolors of Y, C and M are printed while they are superimposed over oneanother in a regular order for each line of all, the tone of thesynthesized colors R, G and B is not changed in some lines, therebymaking a colored image print which is uniform in tone.

And also, since the sequence of superimposition of primary colors M, Cand Y is not changed by the forward or reverse scanning direction in amain scanning, it is possible to make a colored image which is uniformin tone even when one-way printing or bidirectional printing isperformed.

Printing Method According to Second Embodiment

A printing method according to the second embodiment will now bedescribed with reference to FIG. 6 and FIG. 7.

The second embodiment relates to the printing method using the colorprinter 20 as employed by the first embodiment.

FIG. 6 is a flow chart showing steps in the printing method and FIG. 7is a view for explaining print states in respective steps. FIG. 7 showsthe case where the number n of nozzle holes of each group is expressedas n=3, and the nozzle holes capable of discharging ink have entirelydischarged discharge ink.

The color printer 20 shown in FIG. 1 is started up, then the carriage 1is set at a printing start position, thereafter the printing operations,which are the same as in first step ST1 of the first embodiment, areperformed in a first step st1 as shown in FIGS. 6 and 7.

Next, the printing operation, which is the same as in second step ST2 ofthe first embodiment, is performed in a second step st2. Then theprinting operation, which is the same as in third step ST3 of the firstembodiment, is performed in a third step st3.

Further, main scanning is performed in fourth step st4 in a state whereink can be discharged through all nozzle holes of the M group and Cgroup to make a dot print based on the print data while ink isprohibited from being discharged through other nozzle holes, namely,nozzle holes of the Y group after the carriage 1 is subjected toauxiliary scanning by one pitch upon feeding the recording sheet (onepitch sheet feed).

As a result, there is produced a line where the dots are printed whilethey are superimposed over one another in the order of Y and C, and aline where the dots are printed while they are superimposed over oneanother in the order of Y, C and M.

Then the main scanning is performed in fifth step st5 in a state whereink can be discharged through all nozzle holes of the M group to make adot print based on the print data while ink is prohibited from beingdischarged through other nozzle holes after the carriage 1 is subjectedto auxiliary scanning by one pitch sheet feed.

As a result, as shown in FIG. 7, dots are printed while they aresuperimposed over one another in the order of Y, C and M on all linesextending from a leading line to the line of n×3 (n=3 in FIG. 7 and thisis applied hereinafter), and dots are not printed at all on the lineother than those set forth above.

Subsequently, it is judged whether the procedure of program continues ornot, and the program ends if it does not continue while the program goesto sixth step st6 if it continues, where the main scanning is performedin the same condition as in first step st1 after the carriage 1 issubjected to auxiliary scanning by (n-1)×3-1 pitches upon completion ofsheet feed by the same pitch (five pitches in FIG. 7). That is, the mainscanning is performed in a state where ink can be discharged from allnozzle holes of the Y group while it is prohibited from being dischargedthrough other nozzle holes as set forth above.

As a result, the dots are printed while they are superimposed over oneanother in the order of Y, C and M in the line corresponding to thefirst nozzle hole M1 of the M group and all upward lines thereof, andthe line immediately under this line (line corresponding to the firstnozzle hole C1 of the C group), and the print state becomes the same asin first step st1 in the lines therebeneath.

In the next step, namely, in the seventh step, the same operation as insecond step st2 is performed. That is, main scanning is performed in astate where ink can be discharged all nozzle holes of the C group and Ygroup to make a dot print based on the print data while it is prohibitedfrom being discharged through other nozzle holes (all nozzle holes ofthe M group) after the carriage 1 is subjected to the auxiliary scanningby one pitch.

As a result, as shown in FIG. 7, dots are printed while they aresuperimposed over one another in the order of Y, C and M in the linecorresponding to the first nozzle hole M1 of the M group and all linesupward thereof, and the print state becomes the same as in second stepst2 in the line corresponding to the same line and the linestherebeneath.

In the subsequent step, namely, in the eighth step, the same operationas in third step st3 is performed. That is, main scanning is performedin a state where ink can be discharged from all nozzle holes of the M, Cand Y group to make a dot print based on the print data after thecarriage 1 is subjected to auxiliary scanning by one pitch.

As a result, as shown in FIG. 7, dots are printed while they aresuperimposed over one another in the order of Y, C and M in all linesupward of the line corresponding to the first nozzle hole M1 of the Mgroup, and the print state becomes the same as in third step st3 in thesame line and the lines therebeneath.

In such a manner, the program returns to second step st2 upon completionof the execution of fourth step st4, fifth step st5 and sixth step st6,and respective second step st2 to sixth step st6 are circularly executedwhile the program continues. The execution of fifth step st5 may becompleted not making a print.

As a result, dots are printed while they are superimposed over oneanother in the order of Y, C and M in all lines.

The second embodiment has the same effect as the first embodiment.Further, the control of the operations can be simplified compared withthe first embodiment.

However, in the first embodiment, there is a repeated step (ST6) wherethe carriage 1 is subjected to auxiliary scanning by (n-1)×3+1 pitchesupon completion of four steps (ST7, ST3, ST4 and ST5) where therecording sheet is fed pitch by pitch.

Accordingly, the recording sheet is fed by (n-1)×3+5 pitches throughfive steps. On the other hand, in the second embodiment, there is arepeated step where the carriage 1 is subjected to the auxiliaryscanning by (n-1)×3-1 pitches upon completion of four steps (st6, st2,st3 and st4) where the recording sheet is fed pitch by pitch.

Accordingly, the recording sheet is fed by (n-1)×3+3 pitches throughfive steps. As is evident from the above, the first embodiment isslightly more advantageous than the second embodiment in respect ofprinting speed.

In the first embodiment, the dots of YC and M are already printed on theportion of the recording sheet to be printed through the nozzle holes M1and C1 after the recording sheet is fed by (n-1)×3+1 pitches in stepST6, and this printing is performed continuously with the lineimmediately before this line. Accordingly, even if there occurs aprecision error in sheet feeding amount when the recording sheet is fedby (n-1)×3+1 pitches, the influence caused by this error is small,thereby producing an advantage that any streaks produced between theprinted continuous portions are not prominent.

Meanwhile, if there occurs a precison error in the sheet feeding amountwhen the recording sheet is fed by (n-1)×3-1 pitches so as to start theprinting afresh in sixth step sT6 of the second embodiment, theinfluence due to this error appears as it is. For example, therefrequently occurs white streaks or the overlapping of printed dots.

Printing Method According to Third Embodiment, and the Color Printer

Next, a printing method according to the third embodiment of theinvention and the color printer used by this printing method will now bedescribed with reference to FIG. 8 to FIG. 11.

The color printing method of the invention in which the sequence ofsuperimposition of colors is regular and which was explained as thefirst and the second embodiments is hereinafter defined as the "firstprinting method". Further, a color printing method in which the sequenceof superimposition of colors is not regular and which was explained withreference to FIG. 20 as the "third prior art" is defined as the "secondprinting method".

The color printer and the printing method obtained by this color printercan print by arbitrarily selecting either the first or second printingmethod.

The color printer used in this embodiment is the same in mechanism asthe color printer 20 as shown in FIG. 1, but the construction of thecontroller constituting the control system is slightly different.

A controller 12' shown in FIG. 8 has substantially the same constructionas the controller 12 shown in FIG. 3, and hence the components which aresame as those shown in FIG. 3 are denoted by the same reference numeralsand the explanation thereof is omitted here. The controller 12' has afirst gate array 25 and a second gate array 26.

The first gate array 25 is a logical circuit for converting the printdata which is inputted from the host 13 into M, C and Y datacorresponding to the first printing method, and it is the same as thegate array 25 in FIG. 3.

The second gate array 26 is a logical circuit for converting the printdata which is inputted from the host 13 into M, C and Y datacorresponding to the second printing method.

Either the first gate array 25 or the second gate array 26 isarbitrarily selected from these gate arrays 25 and 26 upon reception ofcontrol data from the host 13 or upon the input of a data signal fromthe operation key 16. The selection of either of the gate arrays isdisplayed on the indicator 15.

That is, the controller 12' of the color printer is provided with thefunctions of the first control means and the second control means, andthe function of the selection means thereof.

First of all, the second printing method which was explained withreference to FIG. 20 as the third prior art will now be described againwith reference to the flow chart in FIG. 9.

The color printer shown in FIG. 1 to FIG. 8 is started up, then thecarriage 1 is set at the printing start position, thereafter theoperations, which are the same as those in first to sixth steps ST1,ST2, ST3, ST4, ST5 and ST6 and explained with reference to FIG. 20 asthe third prior art, are sequentially performed in first to sixth stepssT1, sT2, sT3, sT4, sT5 and sT6 of the procedures as shown in FIG. 9.

Then, it is judged whether the program continues or not as shown in FIG.9, and fourth to sixth steps sT4, sT5, sT6 are repeated if the programcontinues, and then seventh and eighth steps sT7 and sT8, which are thesame as those of seventh and eighth steps ST7 and ST8 as third priorart, are subsequently executed after sixth step sT6 if the program doesnot continue. The printing operation is completed in the order of stepsof . . . , sT4, sT5, sT6, sT7 and sT8.

At this time, it is possible to superimpose printed dots of all primarycolors of M, C and Y over one another in all lines of the printed image.However, the sequence of superimposition of the colors is varied in theorder of MYC, CMY and YCM in some lines as explained hereinbefore.Accordingly, the tone of the synthesized colors R, G and B are varied insome lines, thereby deteriorating uniformity of the tone.

Meanwhile, regarding the feeding in the auxiliary scanning, steps sT4,sT5 and sT6 are the same as those of steps of ST4, ST5 and ST6 in thethird prior art while the steps sT4, sT5, sT6 sT4 . . . are executedrepeatedly. The auxiliary scanning by one pitch is performed in steps ofsT5 and sT6, as shown hereinbefore, and the auxiliary scanning by(n-1)×3+1 pitch in fourth step sT4.

Accordingly, the recording sheet is fed in the auxiliary scanningdirection by (n-1)×3+4 pitch between three steps of the repeatedexecution.

Suppose that this is the second printing method, this is compared withthe case of employment of the first printing method of the firstembodiment as explained already. The recording sheet is fed by (n-1)×3+5pitches by executing five steps in the first printing method.Accordingly, if the five steps are converted into 15 steps, therecording sheet is fed by (n-1)×9+15 pitches according to the printingmethod of the first embodiment while it is fed by (n-1)×15+20 pitchesaccording to the second printing method.

Since the time involved in executing one step is mainly determined bythe main scanning time, it is considered to be substantially fixed, andhence the time involved in executing 15 steps is substantially the sameboth in the first printing method and in the second printing method.

During this period, the dots are printed in (n-1)×9+15 lines accordingto the first printing method while the dots are printed in (n-1)×15+20rows according to the second printing method. Accordingly, the printingspeed can be increased in the second printing method.

In the case of n=20 dots are printed in 186 lines according to the firstprinting method while dots are printed in 305 lines according to thesecond printing method, wherein the printing speed in the secondprinting method is 1.64 times as fast as that in the first printingmethod.

FIG. 10 is a flow chart showing an example of printing procedure in thecase where the printing method is selected based on the control datafrom the host 13 in the color recorder having the control system shownin FIG. 8.

The CPU 17 in FIG. 8 executes, after turning power ON. initialization ofthe controller 12' (S100). Then the CPU 17 goes into standby mode whilemonitoring the input of the selection control data from the host 13 viathe interface 22 (S101).

When the selection control data is inputted in step S101, the CPU 17specifies the printing method depending on the content of the selectioncontrol data, and selects either the gate array 25 or the gate array 26in accordance with the printing method and makes the selected gate arrayvalid. The control program for making a record in accordance with thefirst printing method and the control program for making a print inaccordance with the second printing method are separately written intothe program memory 18 as shown in FIG. 8. The CPU 17 selects either ofthe control programs depending on the content of data when the selectioncontrol data is inputted.

In such a manner, the printing method for the printing operation isspecified as either the first printing method or second printing methodin step S102.

Subsequently in step S103, the CPU 17 goes into standby mode whilemonitoring the input of print data from the host 13 via the interface22.

When the print data is inputted from the host 13, the print data isstored in a receiving RGB buffer provided in the data memory 21 in stepS104. Then, the procedures in steps S103 to S105 are repeated until thecompletion of reception of the prescribed amount of print data from thehost 13 (receiving buffers are full) in step S105.

When the CPU 17 discriminates the completion of reception of the printdata in step S105, the print data which was received and temporarilystored in the receiving RGB buffer is subjected to conversion by theselected gate array 25 or 26, and the converted data is stored inrecording M, C and Y buffers provided in the data memory 21 (R, G and Bare converted to M, C and Y). The printing is started in accordance withthe selected printing method upon completion of these procedure steps.

If the inputted print data is M, Y and C color data, such data need notbe converted, but the print can be immediately started in accordancewith the selected printing method.

FIG. 11 is a view showing an example of printing procedure in the caseof selecting the printing method by the input through the operation key16.

The CPU 17 executes, after turning power ON, the initialization of thecontroller 12' (S200). If data for selecting the printing method isinputted when the external operation key 16 is operated, the CPU 17detects this data via the input port 24 for operation key in step S201.

Either the first printing method or second printing method is specifiedin step S202 in the same manner as step S102.

Subsequently, printing is started by the selected printing method afterthe same procedures as those in steps S103 to S106 are executed in stepsS203 to S206.

As mentioned above, according to the color printer of the presentembodiment, it is possible to make a print by arbitrarily selectingeither the first printing method or second printing method. It ispossible to select the appropriate printing method in response to theobject of printing or to the kinds of print data.

For example, it is possible to select the first printing method when thequality of image takes precedence and to select the second printingmethod when printing speed takes precedence or when printing a patternwhere the sequence of superimposition of colors does not influence thequality of image.

In such a manner, it is possible to enhance the applicability and theconvenience of the color printer.

Printing Method According to Fourth Embodiment

A printing method according to the fourth embodiment will be explainedhereinafter.

This method makes a print in accordance with the second printing method(method where sequence of colors is not regular) when the printing modeof the print data is a photographic mode, or with the first printingmethod (method where sequence of colors is regular) when the printingmode of the print data is a graphic mode.

The color printer used in this embodiment has a hard construction whichis the same as the color printer used in the third embodiment in FIG. 8.

FIG. 12 shows an example of printed dots in the photographic mode andthe FIG. 13 shows an example of printed dots in the graphic mode.

FIG. 14 is a flow chart showing the procedures at the host side and theprinter side in the printing method of the fourth embodiment of theinvention.

In the printing method in the fourth embodiment, the power of the host13 is first started up as shown in FIG. 14 to execute the initializationof the host 13 in step S300.

Thereafter, a program for controlling the judgment of the printing mode,described later, and the transmission of the selection control datarelative to the printer is stored in a memory of the host 13 by settingof a printer driver.

Subsequently in step S302, the print data is stored in the data memoryof the host 13 by a scanner or transmission from an external memory.Then in step S303, it is judged whether the printing mode of the printdata is a photographic mode or graphic mode, and the selection controldata corresponding to the result of judgment is transmitted to theprinter.

The photographic mode is chosen if the print data comprises differentcolors which are mixed with one another dot by dot as shown in FIG. 19and the control data for selecting the second printing method whereinthe sequence of colors is not regular is transmitted to the printer viathe interface. If the photographic mode is not choosen, the selectioncontrol data for selecting the first printing method wherein thesequence of colors is regular is transmitted.

If dots of the same colors are gathered in groups as shown in FIG. 13,the photographic mode is not chosen.

Before step S303 is executed at the host side, the printer is started upin the same procedure as explained with reference to FIG. 10 in thethird embodiment to cause the input of the selection control data instep S101 for executing the printing processing procedure to enterstandby mode. When the selection control data is inputted in step S101,the CPU 17 shown in FIG. 8 executes the procedure for specifying theprinting method in step S102 as explained hereinbefore.

At this time, the CPU 17 can allow the indicator to indicate theprinting method as specified.

Subsequently, in step S304 at the host side, the completion of thespecification procedure of the printing method (S102) at the printerside is monitored. Upon completion of the specification procedure, theprint data is transmitted to the printer in step S305.

Accordingly, at the printer side, the printing is started in accordancewith the printing method specified by the selection control data uponcompletion of the execution of the procedures in steps S103 to S105 inthe same manner as in the third embodiment.

According to this embodiment, the printing is made by the secondprinting method wherein the sequence of colors is not regular when theprinting made with the print data is in the photographic mode. Since theprinted dots of the same colors are dispersed minutely in the case ofthe photographic mode, the change of tone does not appear as a pattern,and hence the quality of image is not so deteriorated even in the casewhere the sequence of colors is not regular. Accordingly, it ispreferable to increase the printing speed according to the secondprinting method.

However, the print is made by the first printing method wherein thesequence of colors is regular when the printing mode of the print datais in the graphic mode. In the case of the graphic mode, areas occupiedby the same colors are large, and hence the change of tone clearlyappears when the print is made by the printing method where the sequenceof color is not regular, thereby deteriorating the quality of image.Accordingly, taking the quality of image as a precedent over theprinting speed, there frequently occurs a case where the print is madeby the first printing method where the sequence of color is regular.

As mentioned above, according to the fourth embodiment, it is possibleto make an appropriate print in response to the printing mode of theprint data.

Printing Method According to Fifth Embodiment, and the Color Printerused in the Same

A printing method according to a fifth embodiment and a color printerused in the fifth embodiment will be described hereinafter withreference to FIG. 15 and FIG. 16.

The color printer used in this embodiment has the function to print acommon test pattern in a memory capable of selecting the first printingmethod where the sequence of colors is regular, or the second printingmethod where the sequence of colors are not regular by use of the abovetwo printing methods for selecting the printing method adapted for thesheet media.

FIG. 15 is a block diagram showing an example of construction of thecontrol system of the color printer. A controller 12" for constitutingthe control system comprises, in addition to the controller 12' whichwas used in the third embodiment, a test pattern memory 32 in which dataof the test pattern is stored, a mode selection key 33 for selectingwhether a test mode for printing the test pattern is a normal printingmode for printing normal data or not, and a mode selection input port34.

The color printer used in this embodiment is substantially the same asthe mechanism shown in FIG. 1.

FIG. 16 is a flow chart showing steps of the printing procedure in atest mode of the color printer.

The CPU 17 executes instructions, after turning power ON initializationof the controller 12" shown in FIG. 16 (S400). When data for selectingthe printing method is inputted through the operation key 16, the CPU 17detects the data via the input port 24 in step S401, and specifieseither the first printing method or the second printing method in stepS402.

If control data TD for selecting a test pattern is inputted by the modeselection key 33, the CPU 17 detects this data via the mode selectioninput port 34 in step S403. As a result, the CPU 17 reads the testpattern data from the test pattern memory (ROM) 32 and this data isstored in a receiving RGB buffer provided in the data memory 21.

In steps S405, the procedures in steps S404 and S405 are repeated untilthe CPU 17 discriminates the completion of reception of the prescribedamount of print data (receiving buffers are full) from the test patternmemory 32.

When the CPU 17 discriminates the completion of reception in step S40,the print data of the test pattern stored in the receiving RGB buffer issubjected to conversion by the selected gate array, and the convertedprint data is stored in printing buffers for M, C and Y provided in thedata memory 21 (R, G and B are converted to M, C and Y).

Upon completion of this procedure, the test printing is started by theselected printing method. As a result, the test pattern is printed onthe recording sheet(media) by the selected printing method.

In such a manner, the same test patterns are printed on the same kind ofrecording sheet using the first and second printing methods, and theprinted test patterns are compared with each other, thereby allowing theprinting method adapted for the recording sheet to be selected based onthe print quality, etc.

There is a case where the printing methods must be differentiateddepending on the recording sheet, whether it is a normal sheet of paperor an OHP, for example. If the printing method adapted for a specifickind of recording media is determined in such a manner, control data NDfor selecting a normal printing (printing of print data inputted fromthe host) is inputted by the mode selection key 33. It is possible tomake a print by selecting the printing method adapted for the recordingsheet based on the print data from the host 13 after the test mode iscleared.

According to the color printer of this embodiment, a printing methodadapted for the recording sheet can be easily selected by the test modebefore normal printing is performed, thereby performing the printingefficiently from the beginning without having to perform normal printingagain, which is excellent in indicating quality, etc.

INDUSTRIAL APPLICABILITY

As mentioned above, it is possible to make a print of multiple colorswhich is uniform in image quality by using a small sized color printerusing ink jet heads which are easily manufactured when making a print ofcolors sequenced in superimposition which is regulars even in one-wayprinting or bidirectional printing.

Further, according to the present invention, it is possible to make aprint by arbitrarily selecting the first printing method wherein thesequence of superimposition of colors is regular but the printing speedis slow or the second printing method wherein the sequencesuperimposition of colors is not regular but the printing speed is fast.

Accordingly, a user of the printer can select an appropriate printingmethod in accordance with the object of printing or the kind of printingpattern so that the applicability and convenience of the ink jet typecolor printer can be enhanced.

What is claimed is:
 1. A color printer provided with ink jet headscomprising three trains of nozzle holes for respectively dischargingdifferent colored inks, each train of nozzle holes composed of aplurality of nozzle holes which are arranged at intervals of threepitches in an auxiliary scanning direction, and the nozzle holes of thethree trains of nozzle holes are disposed at equal intervals in a mainscanning direction while shifting every one pitch in the auxiliaryscanning direction wherein said different colored inks are dischargedand sequentially superimposed over one another on a recording medium tosynthesize colors so as to make a color print; whereinthe color printerfurther comprises control means for controlling the ink jet heads tomake a print which is regular in sequence of superimposition of colorsin the manner of; discharging only one colored ink through the nozzlehole of a first train of nozzle holes which is any one of the threetrains of nozzle holes to make a print on the recording medium as theink jet heads are scanned in the main scanning direction in a firststep; discharging ink through the nozzle holes of the first train ofnozzle holes and the nozzle holes of a second train of nozzle holesadjacent to the first train of nozzle holes to make a print on therecording medium as the ink jet heads are scanned in the main scanningdirection while they are shifted by one pitch in the auxiliary scanningdirection relative to the recording medium in a second step; dischargingink through all nozzle holes of the first, second and remaining thirdtrains of nozzle holes to make a print on the recording medium as theink jet heads are scanned in the main scanning direction while they areshifted by one pitch in the auxiliary scanning direction relative to therecording medium in a third step; discharging ink through all nozzleholes of the second and third trains of nozzle holes and only throughthe last nozzle hole of the first train of nozzle holes in the auxiliaryscanning direction to make a print on the recording medium as the inkjet heads are scanned in the main scanning direction while they areshifted by one pitch in the auxiliary scanning direction relative to therecording medium in a fourth step; discharging ink through all nozzleholes of the third train of nozzle holes and only through the lastnozzle holes of the first and second trains of nozzle holes in theauxiliary scanning direction to make a print on the recording medium asthe ink jet heads are scanned in the main scanning direction while theyare shifted by one pitch in the auxiliary scanning direction relative tothe recording medium in a fifth step; discharging ink through all nozzleholes of the first train of nozzle holes and only through the firstnozzle holes of the second and third trains of nozzle holes in theauxiliary scanning direction to make a print on the recording medium asthe ink jet heads are scanned in the main scanning direction while theyare shifted by (n-1)×3+1 pitches (n is the number of nozzle holes ofeach nozzle train) in the auxiliary scanning direction relative to therecording medium in a sixth step; discharging ink through all nozzleholes of the first and second trains of nozzle holes and only throughthe first nozzle hole of the third train of nozzle holes in theauxiliary scanning direction to make a print on the recording medium asthe ink jet heads are scanned in the main scanning direction while theyare shifted by one pitch in the auxiliary scanning direction relative tothe recording medium in a seventh step; executing printing operationssequentially in the third to seventh steps; discharging ink only throughthe last nozzle holes of the second and third trains of nozzle holes inthe auxiliary scanning direction to make a print on the recording mediumas the ink jet heads are scanned in the main scanning direction whilethey are shifted by one pitch in the auxiliary scanning directionrelative to the recording medium in a step following the fifth step whenending the printing; and then discharging ink only through the lastnozzle hole of the third train of nozzle holes in the auxiliary scanningdirection to make a print on the recording medium while the ink jetheads are scanned in the main scanning direction while they are shiftedby one pitch in the auxiliary scanning direction relative to therecording medium so as to end the printing.
 2. A color printer providedwith ink jet heads comprising three trains of nozzle holes forrespectively discharging different colored inks, each train of nozzleholes composed of a plurality of nozzle holes which are arranged atintervals of three pitches in the auxiliary scanning direction, and thenozzle holes of the three trains of nozzle holes are disposed at equalintervals in the main scanning direction while shifting every one pitchin the auxiliary scanning direction wherein said different colored inksare discharged and sequentially superimposed over one another on arecording medium to synthesize colors so as to make a color print,wherein the color printer further comprises:first control means forcontrolling the ink jet heads to make a print which is regular insequence of superimposition of colors in the manner of; discharging onlyone colored ink through the nozzle hole of a first train of nozzle holeswhich is any one of the three trains of nozzle holes to make a print onthe recording medium as the ink jet heads are scanned in the mainscanning direction in a first step; discharging ink through the nozzleholes of the first train of nozzle holes and the nozzle holes of asecond train of nozzle holes adjacent to the first train of nozzle holesto make a print on the recording medium as the ink jet heads are scannedin the main scanning direction while they are shifted by one pitch inthe auxiliary scanning direction relative to the recording medium in asecond step; discharging ink through all nozzle holes of the first,second and remaining third trains of nozzle holes to make a print on therecording medium as the ink jet heads are scanned in the main scanningdirection while they are shifted by one pitch in the auxiliary scanningdirection relative to the recording medium in a third step; dischargingink through all nozzle holes of the second and third trains of nozzleholes and only through the last nozzle hole of the first train of nozzleholes in the auxiliary scanning direction to make a print on therecording medium as the ink jet heads are scanned in the main scanningdirection while they are shifted by one pitch in the auxiliary scanningdirection relative to the recording medium in a fourth step; dischargingink through all nozzle holes of the third train of nozzle holes and onlythrough the last nozzle holes of the first and second trains of nozzleholes in the auxiliary scanning direction to make a print on therecording medium as the ink jet heads are scanned in the main scanningdirection while they are shifted by one pitch in the auxiliary scanningdirection relative to the recording medium in a fifth step: dischargingink through all nozzle holes of the first train of nozzle holes and onlythrough the first nozzle holes of the second and third trains of nozzleholes in the auxiliary scanning direction to make a print on therecording medium as the ink jet heads are scanned in the main scanningdirection while they are shifted by (n-1)×3+1 pitches (n is the numberof nozzle holes of each nozzle train) in the auxiliary scanningdirection relative to the recording medium in a sixth step; dischargingink through all nozzle holes of the first and second trains of nozzleholes and only through the first nozzle hole of the third train ofnozzle holes in the auxiliary scanning direction to make a print on therecording medium as the ink jet heads are scanned in the main scanningdirection while they are shifted by one pitch in the auxiliary scanningdirection relative to the recording medium in a seventh step; executingprinting operations sequentially in the third to seventh steps;discharging ink only through the last nozzle holes of the second andthird trains of nozzle holes in the auxiliary scanning direction to makea print on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in a stepfollowing the fifth step when ending the printing; and then dischargingink only through the last nozzle hole of the third train of nozzle holesin the auxiliary scanning direction to make a print on the recordingmedium while the ink jet heads are scanned in the main scanningdirection while they are shifted by one pitch in the auxiliary scanningdirection relative to the recording medium so as to end the printing;second control means for controlling the ink jet heads to make a printwhich is irregular in sequence of superimposition of colors bydischarging ink through all nozzle holes to make a print on therecording medium while prohibiting ink from being discharged throughrespective first nozzle holes of the two trains of nozzle holes of thethree trains of nozzle holes in the auxiliary scanning direction as theink jet heads are scanned in the main scanning direction, thendischarging ink through all nozzle holes to make a print on therecording medium while prohibiting ink from being discharged onlythrough the first nozzle hole of either of the two trains of nozzleholes in the auxiliary scanning direction as the ink jet heads arescanned in the main scanning direction while they are shifted by onepitch in the auxiliary scanning direction relative to the recordingmedium, and thereafter discharging ink through all nozzle holes of thethree trains of nozzle holes to make a print on the recording medium asthe ink jet heads are scanned in the main scanning direction while theyare shifted by one pitch in the auxiliary scanning direction relative tothe recording medium; and selection means for selecting either the firstcontrol means or the second control means to control the ink jet headswhen the printing is performed.
 3. The color printer according to claim2, wherein the selection control means selects either the first controlmeans or the second control means when an external operation member isoperated.
 4. The color printer according to claim 2, wherein theselection control means includes printing mode judgement means forselecting the printing mode of the print data is a photographic mode ora graphic mode, and for selecting the second control means if theprinting mode is the photographic mode and selecting the first controlmeans if the printing mode is the graphic mode in response to the resultof judgement.
 5. The color printer according to claim 2, furthercomprising a test pattern memory for storing therein test pattern dataand test pattern printing means for reading the test pattern data fromthe test pattern memory to cause the control means selected by theselection means to control the ink jet heads to make a print.
 6. Thecolor printer according to claim 5, further comprising mode selectionmeans for selecting a test mode for printing the test pattern and anormal printing mode for printing normal print data.
 7. A printingmethod using a color printer provided with ink jet heads comprisingthree trains of nozzle holes for respectively discharging differentcolored ink, each train of nozzle holes being composed of a plurality ofnozzle holes which are arranged at intervals of three pitches in anauxiliary scanning direction, and the nozzle holes of the three trainsof nozzle holes are disposed at equal intervals in a main scanningdirection while shifting every one pitch in the auxiliary scanningdirection wherein different colored inks are discharged and sequentiallysuperimposed over one another on a recording medium to synthesize colorsso as to make a color print, the method comprising the following stepsfor making a print which is regular in sequence of superimposition ofcolors;discharging only one colored ink through the nozzle holes of afirst train of nozzle holes which is any one of three trains of nozzleholes to make a print on the recording medium as the ink jet heads arescanned in the main scanning direction in a first step; discharging inkthrough the nozzle holes of the first train of nozzle holes and thenozzle holes of a second train of nozzle holes adjacent to the firsttrain of nozzle holes to make a print on the recording medium as the inkjet heads are scanned in the main scanning direction while they areshifted by one pitch in the auxiliary scanning direction relative to therecording medium in a second step; discharging ink through all nozzleholes of the first, second and remaining third trains of nozzle holes tomake a print on the recording medium as the ink jet heads are scanned inthe main scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in a thirdstep; discharging ink through all nozzle holes of the second and thirdtrains of nozzle holes and only through the last nozzle hole of thefirst train of nozzle holes in the auxiliary scanning direction to makea print on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in afourth step; discharging ink through all nozzle holes of the third trainof nozzle holes and only through the last nozzle holes of the first andsecond trains of nozzle holes in the auxiliary scanning direction tomake a print on the recording medium as the ink jet heads are scanned inthe main scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in a fifthstep; discharging ink through all nozzle holes of the first train ofnozzle holes and only through the first nozzle holes of the second andthird trains of nozzle holes in the auxiliary scanning direction to makea print on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by (n-1)×3+1 pitches (nis the number of nozzle holes of each nozzle train) in the auxiliaryscanning direction relative to the recording medium in a sixth step;discharging ink through all nozzle holes of the first and second trainsof nozzle holes and only through the first nozzle hole of the thirdtrain of nozzle holes in the auxiliary scanning direction to make aprint on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in aseventh step; executing printing operations sequentially in the third toseventh steps; discharging ink only through the last nozzle holes of thesecond and third trains of nozzle holes in the auxiliary scanningdirection to make a print on the recording medium as the ink jet headsare scanned in the main scanning direction while they are shifted by onepitch in the auxiliary scanning direction relative to the recordingmedium in a step following the fifth step when ending the printing; andthen discharging ink only through the last nozzle hole of the thirdtrain of nozzle holes in the auxiliary scanning direction to make aprint on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium so as toend the printing.
 8. A printing method using a color printer providedwith ink jet heads comprising three trains of nozzle holes forrespectively discharging different colored ink, each train of nozzleholes being composed of a plurality of nozzle holes which are arrangedat intervals of three pitches in the auxiliary scanning direction, andthe nozzle holes of the three trains of nozzle holes are disposed atequal intervals in the main scanning direction while shifting every onepitch in the auxiliary scanning direction wherein different colored inksare discharged and sequentially superimposed over one another on arecording medium to synthesize colors so as to make a color print, themethod comprising:a first printing method of making a print which isregular in sequence of superimposition of colors, said method composedof steps of: discharging only one colored ink through the nozzle hole ofa first train of nozzle holes which is any one of three trains of nozzleholes to make a print on the recording medium as the ink jet heads arescanned in the main scanning direction in a first step; discharging inkthrough the nozzle holes of the first train of nozzle holes and thenozzle holes of a second train of nozzle holes adjacent to the firsttrain of nozzle holes to make a print on the recording medium as the inkjet heads are scanned in the main scanning direction while they areshifted by one pitch in the auxiliary scanning direction relative to therecording medium in a second step; discharging ink through all nozzleholes of the first, second and remaining third trains of nozzle holes tomake a print on the recording medium as the ink jet heads are scanned inthe main scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in a thirdstep; discharging ink through all nozzle holes of the second and thirdtrains of nozzle holes and only through the last nozzle hole of thefirst train of nozzle holes in the auxiliary scanning direction to makea print on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in afourth step; discharging ink through all nozzle holes of the third trainof nozzle holes and only through the last nozzle holes of the first andsecond trains of nozzle holes in the auxiliary scanning direction tomake a print on the recording medium as the ink jet heads are scanned inthe main scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in a fifthstep; discharging ink through all nozzle holes of the first train ofnozzle holes and only through the first nozzle holes of the second andthird trains of nozzle holes in the auxiliary scanning direction to makea print on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by (n-1)×3+1 pitches (nis the number of nozzle holes of each nozzle train) in the auxiliaryscanning direction relative to the recording medium in a sixth step;discharging ink through all nozzle holes of the first and second trainsof nozzle holes and only through the first nozzle hole of the thirdtrain of nozzle holes in the auxiliary scanning direction to make aprint on the recording medium as the ink jet heads are scanned in themain scanning direction while they are shifted by one pitch in theauxiliary scanning direction relative to the recording medium in aseventh step; executing printing operations sequentially in the third toseventh steps; discharging ink only through the last nozzle holes of thesecond and third trains of nozzle holes in the auxiliary scanningdirection to make a print on the recording medium as the ink jet headsare scanned in the main scanning direction while they are shifted by onepitch in the auxiliary scanning direction relative to the recordingmedium in a step following the fifth step when ending the printing; andthen discharging ink only through the last nozzle hole of the thirdtrain of nozzle holes in the auxiliary direction to make a print on therecording medium as the ink jet heads are scanned in the main scanningdirection while they are shifted by one pitch in the auxiliary scanningdirection relative to the recording medium so as to end the printing;and a second printing method of making a print which is irregular insequence of superimposition of colors, said method being composed ofsteps of discharging ink through all nozzle holes to make a print on therecording medium while prohibiting ink from being discharged throughrespective first nozzle holes of the two trains of nozzle holes of thethree trains of nozzle holes in the auxiliary scanning direction as theink jet heads are scanned in the main scanning direction, thendischarging ink through all nozzle holes to make a print on therecording medium while prohibiting ink from being discharged onlythrough the first nozzle hole of either of the two trains of nozzleholes in the auxiliary scanning direction as the ink jet heads arescanned in the main scanning direction while they are shifted by onepitch in the auxiliary scanning direction relative to the recordingmedium, and thereafter discharging ink through all nozzle holes of thethree trains of nozzle holes to make a print on the recording medium asthe ink jet heads are scanned in the main scanning direction while theyare shifted by one pitch in the auxiliary scanning direction relative tothe recording medium; and wherein the first control method or the secondcontrol method is arbitrarily or automatically selected to make a print.9. The printing method using the color printer according to claim 8,further comprising a step of selecting the first printing method or thesecond printing method by detecting an operation of an externaloperation member.
 10. The printing method using the color printeraccording to claim 8, further comprising a step of selecting the firstprinting method or the second printing method based on the control datafrom a host.
 11. The printing method using the color printer accordingto claim 8, further comprising steps of judging whether a printing modeof print data is a photographic mode or a graphic mode, and of selectingthe second printing method if the printing mode is the photographic modeand of selecting the first printing method if the printing mode is thegraphic mode.